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Emergence of Coherence in Complex Networks of Heterogeneous Dynamical Systems

Physical Review Letters 2006年第25期96卷 254103-254103页

作者： Juan G. Restrepo Edward Ott Brian R. Hunt Institute for Research in Electronics and Applied Physics University of Maryland College Park Maryland 20742 USA Department of Mathematics University of Maryland College Park Maryland 20742 USA Department of Physics and Department of Electrical and Computer Engineering University of Maryland College Park Maryland 20742 USA Institute for Physical Science and Technology University of Maryland College Park Maryland 20742 USA

We present a general theory for the onset of coherence in collections of heterogeneous maps interacting via a complex connection network. Our method allows the dynamics of the individual uncoupled systems to be either chaotic or periodic, and applies generally to networks for which the number of connections per node is large. We find that the critical coupling strength at which a transition to synchrony takes place depends separately on the dynamics of the individual uncoupled systems and on the largest eigenvalue of the adjacency matrix of the coupling network. Our theory directly generalizes the Kuramoto model of equal strength all-to-all coupled phase oscillators to the case of oscillators with more realistic dynamics coupled via a large heterogeneous network.

关键词： .week ending dynamical systems oscillators coherence per node critical coupling All-to-All Kuramoto Model Maryland USA transition to synchrony

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Characterizing the Dynamical Importance of Network Nodes and Links

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Physical Review Letters 2006年第9期97卷 094102-094102页

The largest eigenvalue of the adjacency matrix of networks is a key quantity determining several important dynamical processes on complex networks. Based on this fact, we present a quantitative, objective characterization of the dynamical importance of network nodes and links in terms of their effect on the largest eigenvalue. We show how our characterization of the dynamical importance of nodes can be affected by degree-degree correlations and network community structure. We discuss how our characterization can be used to optimize techniques for controlling certain network dynamical processes and apply our results to real networks.

关键词： .week ending largest eigenvalue network nodes dynamical processes Maryland USA Dynamical Importance importance of nodes

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Exponential Stability for Cellular Neural Networks with Delay

Exponential Stability for Cellular Neural Networks with Dela...

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13th IEEE International Conference on Electronics, Circuits and Systems (ICECS'2006), vol.3

作者： Jinxiang Yang Shouming Zhong Xingwen Liu College of Computer Science and Technology Southwest University of Nationalities of China Chengdu China School of Applied Mathematics University of Electronic Science and Technology Chengdu China College of Electrical Information Engineering Southwest University of Nationalities of China Chengdu China

This paper investigates the exponential stability of a class of delayed cellular neural networks (DCNN's). By means of appropriately dividing the network state variables into several subgroups, the new sufficient exponential stability condition is derived by constructing Liapunov functional and using the method of the variation of constant. The condition suitable is associated with some initial values and is represented only by some blocks of the interconnection matrix. An example is discussed to illustrate the results.

关键词： Stability Cellular neural networks Delay Symmetric matrices Educational institutions Sufficient conditions State feedback computer science mathematics Integrated circuit interconnections

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Collective excitations of a Bose-Einstein condensate in an anharmonic trap

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Physical Review A 2006年第5期74卷 055601-055601页

作者： Guan-Qiang Li Li-Bin Fu Ju-Kui Xue Xu-Zong Chen Jie Liu Institute of Applied Physics and Computational Mathematics P. O. Box 8009 (28) 100088 Beijing People’s Republic of China Physics and Electronics Engineering College Northwest Normal University 730070 Lanzhou People’s Republic of China Key Laboratory for Quantum Information and Measurements Ministry of Education School of Electronics Engineering and Computer Science Peking University Beijing 100871 People’s Republic of China

We investigate the collective excitations of a one-dimensional Bose-Einstein condensate with repulsive interaction between atoms in a quadratic plus quartic trap. Using variational approaches, the coupled equations of motions for the center-of-mass coordinate of the condensate and its width are derived. Then, two low-energy excitation modes are obtained analytically. The frequency shift induced by the anharmonic distortion, and the collapse and revival of the collective excitations originating from the nonlinear coupling between the two modes, are discussed.

关键词： NONLINEAR DYNAMICS GAS

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Heuristics for estimating contact area of supports in layered manufacturing

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ACM Journal of Experimental Algorithmics 2006年 11卷 1.6–es页

作者： Ilinkin, Ivayio Janardan, Ravi Smid, Michiel Johnson, Eric Castillo, Paul Schwerdt, Jörg Department of Mathematics and Computer Science Rhodes College Memphis 38112 TN United States Department of Computer Science and Engineering University of Minnesota Minneapolis 55455 MN United States School of Computer Science Carleton University Ottawa K1S 5B6 ON Canada Center for Applied Scientific Computing Lawrence Livermore National Laboratory Livermore 94551 CA United States Softwarebüro Bubel GmbH Kirkel 66459 Germany

Layered manufacturing is a technology that allows physical prototypes of three-dimensional(3D) models to be built directly from their digital representation, as a stack of two-dimensional(2D) layers. A key design problem here is the choice of a suitable direction in which the digital model should be oriented and built so as to minimize the area of contact between the prototype and temporary support structures that are generated during the build. Devising an efficient algorithm for computing such a direction has remained a difficult problem for quite some time. In this paper, a suite of efficient and practical heuristics is presented for estimating the minimum contact area. Also given is a technique for evaluating the quality of the estimate provided by any heuristic, which does not require knowledge of the (unknown and hard-to-compute) optimal solution;instead, it provides an indirect upper bound on the quality of the estimate via two relatively easy-to-compute quantities. The algorithms are based on various techniques from computational geometry, such as ray-shooting, convex hulls, boolean operations on polygons, and spherical arrangements, and have been implemented and tested. Experimental results on a wide range of real-world models show that the heuristics perform quite well in practice. © 2006 ACM.

关键词： Algorithm implementation and testing Algorithms Computational geometry E.1 [Data structures] Experimentation F.2.2 [Analysis of algorithms and problem complexity]: Nonnumerical algorithms and problems I.6 [computer-aided engineering] Measurement Performance Theory

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An Improved Electronic Colon Cleansing Method for Detection of Polyps by Virtual Colonoscopy

An Improved Electronic Colon Cleansing Method for Detection ...

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Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： Zigang Wang Xiang Li Lihong Li Bin Li D. Eremina Hongbing Lu Zhengrong Liang Departments of Radiology State University of New York Stony Brook NY USA Department of Radiation Oncology Columbia University New York NY USA Department of Engineering Science and Physics City College of Staten Island City University of New York New York NY USA Applied Mathematics and Statistics State University of New York Stony Brook NY USA Department of Computer Application/BME Fourth Military Medical University Xi'an Shaanxi China Physics and Astronomy State University of New York Stony Brook NY USA Physics and Astronomy State University of New York New York NY USA

Electronic colon cleansing (ECC) aims to segment the colon lumen from the patient abdominal image acquired with colonic material tagging by oral contrast and other means, so that a virtual colon model can be constructed. Virtual colonoscopy (VC) navigates through the colon model looking for polyps in a similar manner as the fiber optic colonoscopy does. We had built an ECC pipeline for the commercial VC system of Viatronix Inc. In this paper, we present an improved ECC method. It is based on a partial-volume image-segmentation framework, which is derived using the well-established statistical expectation-maximization algorithm. The presented ECC method was evaluated by both visual inspection on the cleansed colon lumens and computer-aided detection of polyps (CADpolyp) using 20 patient datasets. Compared to our previous ECC pipeline, this presented new method demonstrates improvement in both visual judgment and CADpolyp

关键词： Colon Colonic polyps Virtual colonoscopy Pipelines Image segmentation Abdomen Optical materials Tagging Navigation Optical fibers

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On adjacent-vertex-distinguishing total coloring of graphs

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Science China mathematics 2005年第3期48卷 289-299页

作者： ZHANG Zhongfu, CHEN Xiang’en, LI Jingwen, YAO Bing, LU Xinzhong & WANG Jianfang college of mathematics and Information Science, Northwest Normal University, Lanzhou 730070, China Department of computer, Lanzhou Normal college, Lanzhou 730070, China Institute of applied mathematics, Lanzhou Jiaotong University, Lanzhou 730070, China college of Information and Electrical engineering, Lanzhou Jiaotong University, Lanzhou 730070, China Institute of applied mathematics, Chinese Academy of Sciences, Beijing 100080, China 1. College of Mathematics and Information Science Northwest Normal University 730070 Lanzhou China 2. Department of Computer Lanzhou Normal College 730070 Lanzhou China 3. Institute of Applied Mathematics Lanzhou Jiaotong University 730070 Lanzhou China 4. College of Information and Electrical Engineering Lanzhou Jiaotong University 730070 Lanzhou China 5. Institute of Applied Mathematics Chinese Academy of Sciences 100080 Beijing China

In this paper, we present a new concept of the adjacent-vertex-distinguishing total coloring of graphs (briefly, AVDTC of graphs) and, meanwhile, have obtained the adjacent-vertex-distinguishing total chromatic number... 详细信息

关键词： graph, proper total coloring, adjacent-vertex-distinguishing total coloring, adjacent-vertex-distinguishing total chromatic number.

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Nesting support vector machinte for muti-classification

Nesting support vector machinte for muti-classification

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International Conference on Machine Learning and Cybernetics, ICMLC 2005

作者： Liu, Bo Hao, Zhi-Feng Yang, Xiao-Wei College of Computer Science and Engineering South China University of Technology Guangzhou 510640 China Department of Applied Mathematics South China University of Technology Guangzhou510640 China

ISBN: (纸本)078039092X

Support vector machines (SVMS) were originally designed for binary classifications. As for multi-classifications, they are usually converted into binary ones, where unclassifiable regions usually exist. To overcome this drawback, a novel method called Nesting Support Vector Machine (NSVMS) for multi-classification is presented in this paper. Our ideas are as follows: Firstly, construct the optimal hyperplanes based on One-against-One algorithm. Secondly, if there exist data points in the middle unclassifiable region, select them to construct optimal hyperplanes with the same hyperparameters. Thirdly, repeat the second step until there are no data points in the unclassifiable regions or the regions disappear. In order to examine the training accuracy and the generalization performance of the proposed algorithm, One-against-One algorithm, Fuzzy Least Square Support Vector Machine (FLS-SVM) and the proposed algorithm are applied to two UCI datasets. The results show that the training accuracy of the proposed algorithm is higher than the others, and its generalization performance is also comparable with them. © 2005 IEEE.

关键词： Classification (of information)

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Online traffic light control through gradient estimation using stochastic fluid models

Online traffic light control through gradient estimation usi...

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作者： Panayiotou, Christos G. Howell, William C. Fu, Michael Department of Electrical and Computer Engineering University of Cyprus Nicosia Cyprus Applied Mathematics Scientific Computation Program Department of Mathematics University of Maryland College Park MD 20742 United States Smith School of Business and Institute for Systems Research University of Maryland College Park MD 20742 United States

ISBN: (纸本)008045108X

in this paper, we consider the problem of dynamically regulating the timing of traffic light controllers in busy cities. We use a Stochastic Fluid Model (SFM) to model the dynamics of the queues formed at an intersection. Based on this model, we derive gradients of the queue lengths with respect to the green/red light lengths within a signal cycle. We report preliminary numerical results comparing the performance of the estimates with finite-difference and smoothed perturbation analysis estimates. Then all estimators are used to optimize the traffic system via Stochastic Approximation. Copyright © 2005 IFAC.

关键词： Stochastic systems

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Abstracts from the 6th International Conference on the engineering of Sport, 10-14 July 2006, Olympic Hall, Munich, Germany Abstracts

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SPORTS engineering 2006年第3期9卷 175-190页

作者： [Anonymous] University of Exeter UK Cranfield University UK University of Ulster UK R&A Rules Limited UK Instituto de Biomecánica de Valencia (IBV) Spain Movement Sciences Group Department of Health Sciences Universiteit Maastricht Netherlands Terra Sports Technology Canada Otto-von-Guericke-University Magdeburg Germany Sports Technology Research Group Loughborough University UK University of Stuttgart Germany Loughborough University UK Sports Engineering CSES Sheffield Hallam University UK Department of Anatomy Bristol University Bristol UK Department of Mechanical Engineering Bristol University Bristol UK Engineering Mechanics United States Air Force Academy Colorado Springs USA Wright Patterson Air Force Base Ohio USA Department Product Development TU Munich Germany Department of Sport Science Otto-von-Guericke University Magdeburg Germany Department of Sport Science University of Vienna Austria Department of Mechanical Engineering Bristol University UK University of Cambridge UK University of Glamorgan UK TUM Sport Equipment & Materials Germany Sports Engineering Research Group University of Sheffield UK Audi Sport USA Royal Melbourne Institute of Technology Australia University of Bath UK University of Wales Institute Cardiff UK Graduate School of Information Science & Engineering Tokyo Institute of Technology Japan Cranfield Centre for Sports Surfaces Cranfield University UK Institute of Mechatronics Chemnitz Germany Institute for Applied Training Science Leipzig Germany Swedish Defence Research Agency Sweden Department of Sport Science University of Innsbruck Austria Department of Engineering Mathematics Geometry & Computer Science University of Innsbruck Austria Department of Mechanics & Mechatronics Vienna University of Technology Austria HTM Tyrolia Schwechat Austria College of Engineering Chubu University Japan Graduate Student of Engineering Chubu University Japan Department of Mechanical Engineering Chubu University Japan The University of We

The primary aim of this study was to assess the feasibility of using a soil laboratory designed for testing of industrial equipment, for the biomechanical assessment of sports movements and footwear. This was achieved by the investigation of the influence of three different footwear types on in-shoe pressures to assess cushioning provided by the footwear for two surface conditions of differing density. Six subjects each performed running trials on the two surfaces in three pairs of footwear: molded boots, boots with studs and trainers. Inshoe pressure data were collected for six running steps for each shoe-surface condition, with peak heel force values used to quantify cushioning. Within each surface condition, similar peak heel force values were obtained for each of the footwear conditions. The comparison of surfaces revealed significantly higher heel impact forces when running on the higher density surface, suggesting a lower cushioning effect of this surface condition. This study demonstrates the potential of the described novel methodology to investigate footwear-surface combinations for controlled natural soil conditions. Combining these data with simultaneously measured pressures at different soil depths will allow the development of surface designs to best cope with the forces applied by the human.

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